The University of Oslo is collaborating with Addis Ababa University (AAU), Ethiopia, through a NORPART exchange program. We are now seeking 1-3 students to work on the population status of the endangered antelope mountain nyala (Tragelaphus buxtoni). Students will use drones to estimate population density, spatial distribution and demographic structure, and assess the population viability as well as evaluating the potential effects of conservation measures. The effects of human disturbance, competition with livestock and trophy hunting may also be assessed. Students from UiO will work together with students from AAU, and be supervised by Dr. Anagaw Atickem, AAU, together with Torbj?rn Ergon and Yngvild Vindenes at CEES, IBV. Dr. Anagaw Atickem has earlier (12 years ago) carried out extensive studies on the mountain nyala, and this will serve as an important reference.
Background information on the conservation status of the mountain nyala and the project is given below (see also https://en.wikipedia.org/wiki/Mountain_nyala).
Interested students should contact Torbj?rn Ergon <t.h.ergon@ibv.uio.no> for further information and discussion.
Conservation status of the endangered mountain nyala in the Bale mountains of Ethiopia
The charismatic mountain nyala (Tragelaphus buxtoni) is an endangered antelope endemic to the Ethiopian highlands. There is increasing human and livestock grazing impact on the core mountain nyala populations. While the Bale Mountains National Park (BMNP) encompasses a large area (2,200 km2), the park is increasingly affected by human settlements and large numbers of livestock. The human population in the park has escalated from only 2,500 households during the park establishment in 1970 to 20,000 households with over 168,000 heads of livestock in 2007 and increasing since then. Mountain nyala has previously been classified as a browser and should therefore have a low dietary overlap with cattle. A detailed study of the foraging ecology of mountains nyala in 17 VHF collared individuals, however, revealed that mountain nyala is rather a mixed feeder where females are more of grazers, and hence a higher potential of competition with grazing livestock. The study also reveals high spatial overlap between mountain nyala and cattle and negative correlation in abundance of cattle and mountain nyala.
Mountain nyala is also still used as an important trophy. Trophy sport hunting must be biologically sound and sustainable in order to be an effective conservation tool (Sparrowe, 1990). Unsustainable harvesting may represent a substantial threat to population viability. One particular example is the collapse of the critically endangered saiga antelope (Saiga tatarica tatarica) due to lower number of males due to selective poaching for their horns (Milner-Gulland et al., 2003). Only in the three hunting concessions (Abasheba, Odobullu and Hanto), over 200 males were hunted from a total population size of 2200 individuals during the last 12 years. Currently, the Ethiopian Wildlife Conservation Department assumes that the population can sustain a 5% annual off take – which is reasonable only if the population is stable and there are good census data. We expect that mountain nyala is sensitive of trophy hunting for several reasons. First, a small population is obviously vulnerable to harvesting. Second, because the mountain nyalas do not form large harems, the density of males may limit female reproduction. The sex composition of mountain nyala which is 1 male to 2.2 females. Even in polygamous mating system where one male can inseminate several females, a certain number of males are needed per female for successful breeding.
Monitoring the population size and age sex composition of mountain nyala, and livestock density is an important baseline data to lead the conservation management effort of the species. In 2009, we estimated the population size of 3800 individuals in six isolated sites of the Bale mountains which has been almost two times estimate of the previous population estimates (Atickem et al., 2011). We got the largest population of mountain nyala in the relict mountains some 60 km of the Bale mountains national park which has been very much underestimated for its population size. Regardless of the good news for the discovery of large population in the eastern dense forest, we have reported our deep worries to the Ethiopian Wildlife Conservation Authority on the potential negative effect of the ongoing trophy hunting on the survival of the species as a result of small population size, age sex composition and nature of mating system in the species. Our second concern is the habitat loss by extensive grazing of livestock in core areas of the mountain nyala. We found out that the livestock density was 20 times higher than the mountain nyala density in some of the mountain nyala localities which can affect the survival of mountain nyala though exploitative and interference competition (Atickem and Loe, 2013). Our study on bases of microsatellite marker also reveals there is limited dispersal between the isolated mountain nyala populations as a result of expanding human settlement (Atickem et al., 2013).
It has been now 12 years since we have studied the distribution pattern and population estimate of the mountain nyala. With this project, we aim to re-assess the population size in each of the isolated mountain nyala localities to assess the trend of the population size and livestock density.
References
Atickem, A. et al. (2011) ‘Estimating population size and habitat suitability for mountain nyala in areas with different protection status: Conservation of mountain nyala’, Animal Conservation, 14(4), pp. 409–418. doi:10.1111/j.1469-1795.2011.00437.x.
Atickem, A. et al. (2013) ‘Population genetic structure and connectivity in the endangered Ethiopian mountain Nyala (Tragelaphus buxtoni): recommending dispersal corridors for future conservation’, Conservation Genetics, 14(2), pp. 427–438. doi:10.1007/s10592-013-0450-6.
Atickem, A. and Loe, L.E. (2013) ‘Livestock-wildlife conflicts in the Ethiopian highlands: assessing the dietary and spatial overlap between mountain nyala and cattle’, African Journal of Ecology, p. n/a-n/a. doi:10.1111/aje.12126.